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The preparation, microstructure and mechanical properties of ZTA particles reinforced Fe matrix composites (ZTAP/Fe composites) were systematically investigated. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to analyze the microstructure and phase constituents, the hardness (H), Young's modulus (E) and plasticity factor (δA) were determined as well. The nickel-chromium double-layer coated ZTAP of core-shell structure was prepared by electroless plating and multi-arc ion plating technologies. The modified ZTAP is consisted of the α-Al2O3, t-ZrO2, α-Cr and γ-Ni phases. In addition, the compressive strength of ceramic preforms is high due to a compact sintering neck formed among ZTAP during high temperature sintering. The preferred sintering process for ZTA ceramic preforms is determined as 1350 °C + 1 h, in this case the preforms show the remarkable porosity and highest compressive strength which are 27.8% and 35.0 MPa, respectively. The interfacial metallurgical chemical reactions occurred during infiltration casting process, which ensure the excellent metallurgical interfacial bonding of the ZTAP/Fe composites. The interface contains double transition layers, which refer to silicate and CrFe phases, respectively. The H, E and δA of interfacial double transition layers were measured by the nano-indentation method, the values of which are situated between the ZTAP and iron matrix.

NiCrAlY coatings were fabricated by atmospheric plasma spraying. The influence of the heat treatment on the corrosion–wear behavior of the coatings in artificial seawater was investigated. The microstructure of the coatings became denser and more homogeneous after the heat treatment. After heat treatment at 1100 °C, the coating had the fewest pores and cracks and the oxide dispersive strengthening phase of Y2O3 was clearly increased to form a layer approximately 10 nm thick and uniformly distributed in the matrix. The heat treatment effectively improved the microhardness and corrosion–wear properties of the coatings. This coating had the highest microhardness of 371.1 HV, the lowest friction coefficient, and a wear rate of 0.24 and 1.01 × 10−6 mm3/Nm and the lowest corrosion rate after heat treatment at 1100 °C, giving it excellent corrosion–wear properties.

Atmospheric plasma spraying (APS) was taken to fabricate the NiCrAlY coating. The corrosion-wear properties of NiCrAlY coating was measured respectively under deionized water, artificial seawater, NaOH solution and HCl solution. Experimental results presented that the as-sprayed NiCrAlY coating consisted of Ni3Al, nickel-based solid solution, NiAl and Y2O3. In deionized water, the coating with the lowest corrosion current density (icorr) of 7.865 &times, 10&minus, 8 A/cm2 was hard to erode. Meanwhile, it presented a lower friction coefficient and the lowest wear rate. In HCl solution, NiCrAlY coating gave the highest corrosion current density (icorr) of 3.356 &times, 6 A/cm2 and a higher wear rate of 6.36 &times, 6 mm3/Nm. Meanwhile, the emergence of Al(OH)3 on the coating surface could reduce the direct contact between the counter ball and sample effectively, which was conducive to the lowest friction coefficient of 0.24.

BaO and TiO2 reacted and produced BaTiO3 in the process of sintering. As a result, the diffraction peaks of BaTiO3 became stronger with the increasing BaO/TiO2 contents. The diffraction peaks of NiAl shifted smaller angle to left with the addition of BaO/TiO2. Meanwhile, the lattice distortion obviously occurred in the composite structure. The composites with the addition of BaO/TiO2 presented high microhardness and yield strength as well. The composite with 20% BaO/TiO2 had the highest microhardness value and yield strength of 474.5 HV and 2786 MPa, respectively. The friction coefficient and wear rate of the composites decreased with the addition of BaO/TiO2 and the NiAl-30% BaO/TiO2 composite had the lowest friction coefficient at 800 °C test temperature. The BaTiO3 was decomposed to BaO and TiO2 during high temperature sliding.

The work of adhesion (Wad), interfacial fracture toughness ( K I c int ), and electronic structure of the Fe(100)//MCs(100) (M = Ti and V) interfaces have been investigated by means of first-principles calculations. Considering two types of interfaces (type 1 and 2), two MCs (TiC and VC) and three different atomic stacking sequences (Fe-on-M, Fe-on-C and Bridge), totally twelve candidate interfacial configurations were analyzed. It is found that the Wad decreases with the order of Fe-on-C > Bridge > Fe-on-M. With the larger Wad, the type 2 Fe//MCs interfaces are more stable than type 1 Fe//MCs interfaces, in which the Fe-on-C site for type 2 Fe//VC interfaces belongs to the most stable interfacial configuration. Based on the Griffith's theory, the mechanical failure of both type 1 and type 2 Fe//TiC interfaces are more inclined to initiate at the interface. While for the Fe-on-C and Bridge site of both type 1 and type 2 Fe//VC interfaces, the mechanical failure will occur at the VC bulk phases rather than at the interface. Besides, the interfacial fracture toughness of Fe-on-C site for the type 2 Fe//VC structure is the best. The interfacial bonding character of Fe-on-C site for both Fe//TiC and Fe//VC interfaces have been investigated based on the electronic density of states and charge density difference. A mixed covalent/ionic/metallic bonding is revealed between iron and transition metal carbides. Further analysis of mulliken population and magnetic moment of interfacial atoms indicates that the Fe//VC interfaces show higher bonding strength than Fe//TiC interfaces.